I don't have any information how big was Ogier's role on building Polo. Could Polo be different (worse) car without Ogier? I have no idea.
Ogier must have good understanding how to set-up car. No doubt about that. 6 titles didn't just fall to his lap.
Are those as good as Tänak, who have been working as mechanic and can talk "their language"? I also don't know that answer, but for me it seems, that Tänak can be better in that.